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Do not use in-place updates for statistics import.

Browse Source 
The use of in-place updates was originally there to follow the
precedent of ANALYZE and to reduce the potential for bloat on
pg_class. Per discussion, it's not worth the risks.

Reported-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/cpdanvzykcb5o64rmapkx6n5gjypoce3y52hff7ocxupgpbxu4@53jmlyvukijo
pull/201/head
Jeff Davis 10 months ago
parent 3ce357584e
commit f3dae2ae58
3 changed files with 47 additions and 177 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 138
      src/backend/statistics/relation_stats.c
  2. 53
      src/test/regress/expected/stats_import.out
  3. 33
      src/test/regress/sql/stats_import.sql

138
src/backend/statistics/relation_stats.c
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@ -48,14 +48,13 @@ static struct StatsArgInfo relarginfo[] =
[NUM_RELATION_STATS_ARGS] = {0}
};
static bool relation_statistics_update(FunctionCallInfo fcinfo, int elevel,
bool inplace);
static bool relation_statistics_update(FunctionCallInfo fcinfo, int elevel);
/*
* Internal function for modifying statistics for a relation.
*/
static bool
relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
relation_statistics_update(FunctionCallInfo fcinfo, int elevel)
{
bool result = true;
Oid reloid;
@ -66,6 +65,12 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
bool update_reltuples = false;
BlockNumber relallvisible = 0;
bool update_relallvisible = false;
HeapTuple ctup;
Form_pg_class pgcform;
int replaces[3] = {0};
Datum values[3] = {0};
bool nulls[3] = {0};
int nreplaces = 0;
if (!PG_ARGISNULL(RELPAGES_ARG))
{
@ -110,101 +115,52 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
*/
crel = table_open(RelationRelationId, RowExclusiveLock);
if (inplace)
ctup = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
if (!HeapTupleIsValid(ctup))
{
HeapTuple ctup = NULL;
ScanKeyData key[1];
Form_pg_class pgcform;
void *inplace_state = NULL;
bool dirty = false;
ScanKeyInit(&key[0], Anum_pg_class_oid, BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(reloid));
systable_inplace_update_begin(crel, ClassOidIndexId, true, NULL, 1, key,
&ctup, &inplace_state);
if (!HeapTupleIsValid(ctup))
elog(ERROR, "pg_class entry for relid %u vanished while updating statistics",
reloid);
pgcform = (Form_pg_class) GETSTRUCT(ctup);
if (update_relpages && pgcform->relpages != relpages)
{
pgcform->relpages = relpages;
dirty = true;
}
if (update_reltuples && pgcform->reltuples != reltuples)
{
pgcform->reltuples = reltuples;
dirty = true;
}
if (update_relallvisible && pgcform->relallvisible != relallvisible)
{
pgcform->relallvisible = relallvisible;
dirty = true;
}
if (dirty)
systable_inplace_update_finish(inplace_state, ctup);
else
systable_inplace_update_cancel(inplace_state);
heap_freetuple(ctup);
ereport(elevel,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("pg_class entry for relid %u not found", reloid)));
table_close(crel, RowExclusiveLock);
return false;
}
else
{
TupleDesc tupdesc = RelationGetDescr(crel);
HeapTuple ctup;
Form_pg_class pgcform;
int replaces[3] = {0};
Datum values[3] = {0};
bool nulls[3] = {0};
int nreplaces = 0;
ctup = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
if (!HeapTupleIsValid(ctup))
{
ereport(elevel,
(errcode(ERRCODE_OBJECT_IN_USE),
errmsg("pg_class entry for relid %u not found", reloid)));
table_close(crel, RowExclusiveLock);
return false;
}
pgcform = (Form_pg_class) GETSTRUCT(ctup);
if (update_relpages && relpages != pgcform->relpages)
{
replaces[nreplaces] = Anum_pg_class_relpages;
values[nreplaces] = UInt32GetDatum(relpages);
nreplaces++;
}
pgcform = (Form_pg_class) GETSTRUCT(ctup);
if (update_reltuples && reltuples != pgcform->reltuples)
{
replaces[nreplaces] = Anum_pg_class_reltuples;
values[nreplaces] = Float4GetDatum(reltuples);
nreplaces++;
}
if (update_relpages && relpages != pgcform->relpages)
{
replaces[nreplaces] = Anum_pg_class_relpages;
values[nreplaces] = UInt32GetDatum(relpages);
nreplaces++;
}
if (update_relallvisible && relallvisible != pgcform->relallvisible)
{
replaces[nreplaces] = Anum_pg_class_relallvisible;
values[nreplaces] = UInt32GetDatum(relallvisible);
nreplaces++;
}
if (update_reltuples && reltuples != pgcform->reltuples)
{
replaces[nreplaces] = Anum_pg_class_reltuples;
values[nreplaces] = Float4GetDatum(reltuples);
nreplaces++;
}
if (nreplaces > 0)
{
HeapTuple newtup;
if (update_relallvisible && relallvisible != pgcform->relallvisible)
{
replaces[nreplaces] = Anum_pg_class_relallvisible;
values[nreplaces] = UInt32GetDatum(relallvisible);
nreplaces++;
}
newtup = heap_modify_tuple_by_cols(ctup, tupdesc, nreplaces,
replaces, values, nulls);
CatalogTupleUpdate(crel, &newtup->t_self, newtup);
heap_freetuple(newtup);
}
if (nreplaces > 0)
{
TupleDesc tupdesc = RelationGetDescr(crel);
HeapTuple newtup;
ReleaseSysCache(ctup);
newtup = heap_modify_tuple_by_cols(ctup, tupdesc, nreplaces,
replaces, values, nulls);
CatalogTupleUpdate(crel, &newtup->t_self, newtup);
heap_freetuple(newtup);
}
ReleaseSysCache(ctup);
/* release the lock, consistent with vac_update_relstats() */
table_close(crel, RowExclusiveLock);
@ -219,7 +175,7 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel, bool inplace)
Datum
pg_set_relation_stats(PG_FUNCTION_ARGS)
{
relation_statistics_update(fcinfo, ERROR, false);
relation_statistics_update(fcinfo, ERROR);
PG_RETURN_VOID();
}
@ -243,7 +199,7 @@ pg_clear_relation_stats(PG_FUNCTION_ARGS)
newfcinfo->args[3].value = UInt32GetDatum(0);
newfcinfo->args[3].isnull = false;
relation_statistics_update(newfcinfo, ERROR, false);
relation_statistics_update(newfcinfo, ERROR);
PG_RETURN_VOID();
}
@ -261,7 +217,7 @@ pg_restore_relation_stats(PG_FUNCTION_ARGS)
relarginfo, WARNING))
result = false;
if (!relation_statistics_update(positional_fcinfo, WARNING, true))
if (!relation_statistics_update(positional_fcinfo, WARNING))
result = false;
PG_RETURN_BOOL(result);

53
src/test/regress/expected/stats_import.out
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@ -143,39 +143,6 @@ WHERE oid = 'stats_import.test'::regclass;
18 | 401 | 5
(1 row)
-- test MVCC behavior: changes do not persist after abort (in contrast
-- to pg_restore_relation_stats(), which uses in-place updates).
BEGIN;
SELECT
pg_catalog.pg_set_relation_stats(
relation => 'stats_import.test'::regclass,
relpages => NULL::integer,
reltuples => 4000.0::real,
relallvisible => 4::integer);
pg_set_relation_stats
-----------------------
(1 row)
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
relpages | reltuples | relallvisible
----------+-----------+---------------
18 | 401 | 5
(1 row)
BEGIN;
SELECT
pg_catalog.pg_clear_relation_stats(
'stats_import.test'::regclass);
pg_clear_relation_stats
-------------------------
(1 row)
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
@ -836,25 +803,6 @@ WHERE oid = 'stats_import.test'::regclass;
(1 row)
-- ok: just relpages
SELECT pg_restore_relation_stats(
'relation', 'stats_import.test'::regclass,
'version', 150000::integer,
'relpages', '15'::integer);
pg_restore_relation_stats
---------------------------
t
(1 row)
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
relpages | reltuples | relallvisible
----------+-----------+---------------
15 | 400 | 4
(1 row)
-- test non-MVCC behavior: new value should persist after abort
BEGIN;
SELECT pg_restore_relation_stats(
'relation', 'stats_import.test'::regclass,
'version', 150000::integer,
@ -864,7 +812,6 @@ SELECT pg_restore_relation_stats(
t
(1 row)
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;

33
src/test/regress/sql/stats_import.sql
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@ -100,27 +100,6 @@ SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
-- test MVCC behavior: changes do not persist after abort (in contrast
-- to pg_restore_relation_stats(), which uses in-place updates).
BEGIN;
SELECT
pg_catalog.pg_set_relation_stats(
relation => 'stats_import.test'::regclass,
relpages => NULL::integer,
reltuples => 4000.0::real,
relallvisible => 4::integer);
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
BEGIN;
SELECT
pg_catalog.pg_clear_relation_stats(
'stats_import.test'::regclass);
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
@ -649,22 +628,10 @@ FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
-- ok: just relpages
SELECT pg_restore_relation_stats(
'relation', 'stats_import.test'::regclass,
'version', 150000::integer,
'relpages', '15'::integer);
SELECT relpages, reltuples, relallvisible
FROM pg_class
WHERE oid = 'stats_import.test'::regclass;
-- test non-MVCC behavior: new value should persist after abort
BEGIN;
SELECT pg_restore_relation_stats(
'relation', 'stats_import.test'::regclass,
'version', 150000::integer,
'relpages', '16'::integer);
ABORT;
SELECT relpages, reltuples, relallvisible
FROM pg_class

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